Hysteresis in Sodium-ion Batteries: Temperature and Relaxation Time Effects

This study investigates the impact of temperature and relaxation time on sodium-ion battery hysteresis. To achieve the latter, accurate characterization of the relationship between open-circuit voltage and state-of-charge was implemented. This relationship was further modeled using the MATLAB curve fitting toolbox keeping the root mean squared error below 5%. The experimental results reveal significant hysteresis levels, particularly at low state-of-charge values, reaching a maximum of 0.2252V. In addition, hysteresis diminishes with increasing temperature and relaxation time. These results underscore the importance of accounting for hysteresis and its variations when accurately estimating state-of-charge and optimizing battery performance.